Thinking of fitting a servo....

[Bluevan]

As we ain't getting any younger, and the effort to stop the old girl in fast traffic gets harder, I'm thinking seriously about fitting a brake servo. (We have the 8" Wolseley drums on the front, already). She stops fine, but effort is needed.

So I'm wondering if there is an 'How-to' on here already about fitting a servo yourself, that someone can point me to?
If not, what are the experiences of members who've fitted one?
Is it okay to take one s/h off a suitable scrap vehicle and fit it yourself, and are any special 'bits' needed?
Or is it a lot less trouble to buy a new kit from your smiling Morris Parts dealer?

Being retired now I have a bit more time to do jobs, and hope to be doing a bit of upgrading within the next year or two, so a servo looks like it might be a good thing to start with.

[bmcecosse]

Wolseley front drums are 9" - not 8". Are you sure you have W drums? They certainly don't need a servo in my experience - although I did have one set of shoes that needed more push than others. I suggest perhaps a new set of shoes will solve your problem. Servo can of course be fitted- but due to the slightly odd brake piping layout of a Minor (two feeds - one to the rear and one to the front) some fairly serious re-piping is required. I suggest using a servo from a scrappy will be false economy.... and of course you need to drill and tap a take off in the inlet manifold - unless it's there already.

[Bluevan]

Thanks for the useful reply.
The front drums probably are 9" then, I haven't measured them in years! The shoes seem to wear very slowly. But they were certainly from a Wolseley, and I think last time I had a local firm make them up, as the originals are quite hard to find.
The van is fine around town, but fast A roads are a bit of a pain - you leave a nice safe stopping distance, and then someone overtakes and slots in sharpish, and a sharp push on the brakes is required. I guess it's partly because we have a slightly more modern vehicle too, and notice the big difference in ease of braking.

I'll pull the shoes on the front and take a look, just in case the cylinders are binding a bit, and not working over their full throw.

What I did wonder about is how the Morris floor master cylinder is coupled up to a standard brake servo?
Most servos have their master cylinder mounted on top or alongside, operated by the footpedal, which is generally fitted the opposite way around to the Morris pedals. I take it a servo in a Morris would be operated remotely?

There's also the interesting question of whether it would be practical to fit a dual-circuit system, so that each circuit operated diagonally, or one to the front and one to the back, giving greater braking safety than the single-line system. This would need a dual output master cylinder though, so perhaps rather a lot of work on the bulkhead, not to mention the pedal shaft, etc.

[simmitc]

As had been said on here many toimes, a servo will not improve braking, but will make it easier to operate. reducing the pedal pressure required to schieve the same braking as before. That seems to be what you want, so a servo is a sensible way to go. Most of the normal suppliers sell the complete kit ready to go; and it comes with instructions, albeit generic and not specifically Minor.

If you apply servo to front only, then there is not so much work, but I have always found that servo all round is best, so:
Disconnect rear pipe and either fit a non drilled cap to the rear of the master cylinder, or block the outlet with a bleed nipple.
Replace existing side entry pipe with a new one running to the servo input. From the servo output, pipe to a T-connector and then (a) to the rear axle and (b) to the existing three way union for the front.
Mount the servbo on the inner right hand wing so that it is away from exhaust. It's easier to mount it on the floor, but then it will prevent removal of the starter motor (been there, done that ).
Drill and tap manifold to fit vacuum take off (remove form engine first to avoid swarf being ingested).

Staffordshire Vehicle Components do a dual circuit output servo that takes a single input, but I have never fitted one.

Good luck.

[bmcecosse]

Or just try some new shoes..... as you say the ones on the car are many years old. The W brakes at 9" are of course a bit unbalanced with the original 7" rear drums - these should really be uprated to the W 8" rear drums - a job I never got round to doing even though I had the parts. The result is that the front brakes tend to do virtually all the braking, and the rears very little. Thus a tendency to lock the front wheels quite easily (especially with the years old skinny tyres I had ). I fear that fitting a servo may make this situation worse by applying even more front force, and causing even worse front wheel locking.

[Bluevan]

Thanks for that; it sounds encouraging!

I guess the first thing is to overhaul the brakes and check everything is working as it should. Then if we still feel we need a servo - which I think we will - I can look at what servo kits are available.
Before obtaining and fitting such a kit, maybe I'll take a look at how other owners who have a servo fitted have routed their pipes, and see if one way is better/easier than another, etc.

Many thanks for the clear directions re the master cylinder, and for the tip about dual-output servos. I see SVC don't list such a part at the present time on their website, but no doubt they would be able to advise whether they could get one in future. I'll try and do a bit more research on dual-outputs before going into it any further.

[Bluevan]

Yes, the 8" Wolseley drums swapped onto the rear axle sound a good safe move to make, maybe even before getting a servo fitted. So thanks for that advice.
I shall have to check that out - do the Morris wheel cylinders still fit okay, or are W ones necessary, as on the front?
Never had any problems locking up at either end, but we don't drive her like a Mini - not these days, anyway!

[Declan_Burns]

Here's the diagram that is supplied with the servo kit from ESM.
Regards
Declan[frame][/frame]

[philthehill]

Whilst the Minor 8" front drums can be fitted and used with the Wolseley rear brakes the brake back plates are different and require Wolseley rear brake cylinders.
It should be noted that the brake cylinder pipe threads and union nipple on the end of the pipe into the cylinder are different to the Minor.
Phil

[oliver90owner]

The comment referring to not driving like a mini is irrelevant. The brakes must be balanced/matched in order not to exacerbate any instance requiring an emergency stop. Likewise locking the wheels is a bit of a red herring. You may be able to lock the fronts, even without a servo; the only difference would be the pedal pressure required would be less with a servo than without.

Dual circuit brakes would likely be split front and rear, rather than diagonally - think here of the possible need for pressure regulation for the rear brakes, to avoid rear lock-up.

Direct and indirect servos would require different installation solutions. Indirect dual circuit? Not come accross any! While servoing only the front brakes may be simpler, the balance of front to rear may be problematic? The braking system was balanced sufficiently when installed all those years ago. Alterations most certainly need careful consideration to detail.

[bmcecosse]

As Phil says - you need the W rear backplates and shoes (rare as rocking horse poo...but 8" front shoes can be modified to fit) at the rear. Only the 8" drums from the front are the same.

[mowogg]

Its probably worth checking the bore size on the master cyclinder. If an earlier 7/8 cylinder has been fitted pedal pressure will be higher. It will be easier to swap this first of this is the case.

[Bluevan]

Thanks for all the replies - lots to think about there!

A bit puzzled over all the warnings about lockup. Never had brake lockup in all the years I can remember, including those when we carried heavier loads than the van was designed for, and those years since we changed the front brakes to Wolseley in 1998.
If lockup may occur so readily, what happens to those Minors fitted with disc brakes on the front? Without ABS, presumably?
And with standard skinny 7" Minor drums on the back?
I've talked to a few disc-braked owners at shows and meetings, but none mentioned, so far as I can recall, anything about their brakes locking up. Most had servos fitted as part of the changeover too, which presumably would have caused lockup earlier than without?

Re the rear brakes, if Wolseley brake parts are so hard to find, are there any easier alternatives? We got our front brakes from a Wolseley 1500 quite some years ago, in the summer of '98, and they were not plentiful then. To put it mildly.

I will check the master cylinder bore size - our present one was fitted in 2006, from Bull Motif Spares, I think. I remember having to grind down the shoulders of the housing a couple of mm to get it into the chassis channel...

[mowogg]

you may find this previous link of interest

http://www.mmoc.org.uk/viewtopic.php?f= ... 3&start=15

I run a similar set up to yours with the earlier master cylinder. my pedal pressure is firm- one day I will replace the master cylinder. the earlier type was all that was available at the time when the last one failed.

If my understanding is correct the dangerous brake lock up is at the rear. The table in the above link would suggest disc brake set ups are more vulnerable to this. Perhaps others can comment but that would suggest your current set up is a lower risk to rest lock up than a standard car. Perhaps just conncentrate on the servo as planned?

[Bluevan]

Thanks for the link, Mowogg. Very interesting.
The chart shows there is far more to it than just brake shoe & drum size; obviously many factors here to take into account!

As you say, probably best to continue with the present setup, get everything working efficiently, and then fit a servo and see how it goes.
(It's off the road on SORN at the moment, as there are several little jobs that need looking at...)

[philthehill]

Whilst the charts in the above attached link are useful the biggest problem with the Minor is the position of the engine which is in front of the front axle pivot point - so when hard braking is undertaken the turning reaction is for the weight to come off/ lighten the rear end so braking grip is lost.
The turning reaction will get worse if the front brakes are upgraded to say discs and the rear left as original - In my experience (and my brakes have had to work harder than the average Minor) the rear must also be upgraded to say Wolseley 1500 rear brakes to maintain the front/rear balance and help reduce the turning reaction.
Whilst not suitable for many cars transferring weight were possible from the front of the car to the rear of the car is of great help.
Phil

[simmitc]

On the Travellers, I have Marina discs on the front, standard Minor on the rear, servo to all. In close to 400K miles I have never suffered from rear lock up.

[mowogg]

Excellent feedback from all.

Having never seen ( i was out but a couple of times) the rare woolsey brakes. how feasible is it to make one out of a set of front 8 inch brakes. in an ideal world this could look to retain standard minor cylinders?

[mowogg]

sorry for the mispellong of wolseley. I blame the auto spell on my phone

[philthehill]

Here is a picture of Wolseley 1500 rear brakes fitted to a Minor rear axle.
The Wolseley back plate has to be turned and changed from side to side to suit the Minor handbrake linkage.
The conversion is easy but the Wolseley cylinder brake pipe unions have a different thread and nipple shape to the Minor so new brake pipes required
Replacement brake cylinders are not cheap.
As regards converting the Minor 8" front back plates whilst not impossible as everything is possible it is and will not be an easy conversion.
Phil[frame][/frame]